成像光谱仪扫描镜运动准确度测量

扫描镜的运动准确度直接影响成像光谱仪对地运动补偿效果,为此研制了一套扫描镜运动准确度测试设备对其进行测量.首先分析了扫描镜的运动补偿原理,从理论上给出了运动补偿曲线;随后以15 m地面像元分辨率和系统调制传递函数下降2%作为依据分别确定了扫描镜的位置和速度准确度要求,列出了扫描镜运动补偿倍数与相对转速误差的关系.基于检定设备1/3法则提出了扫描镜运动准确度测试设备技术指标要求,接着以0.8″绝对式光电编码器为核心建立了一套扫描镜运动准确度测试装置,并从测试方法误差和编码器测角误差两方面对测试装置测角和测速准确度进行了详细分析;最后采用研制的测试装置对扫描镜的运动准确度进行了测量试验.试验结果表明扫描镜位置准确度优于3″±1.2″,4倍补偿时速度准确度为5.6%±1.29%,6倍补偿时速度准确度为3.85%±1.29%,满足成像光谱仪对扫描镜运动准确度要求.外场成像图像证明本文提出的扫描镜运动准确度测量方法及设备可用于成像光谱仪扫描镜的性能检测与验收.

Motion Precision Measurement of Imaging Spectrometer's Scanning Mirror

Motion precision of scanning mirror is vital for motion compensation results of imaging spectrometer. So a set of scanning mirror testing equipment was developped to test scanning mirror's motion precision. Firstly, the motion compensation principle was analyzed and the theory motion compensation curve was given. Then according to 15 m GSD and 2% degradation of system MTF, the scanning mirror's position and speed precision target was confirmed. At the same time the relationship between motion compensation times and relative rotation error was outlined. Based on 1/3 principle, the guide line of scanning mirror's motion precision testing equipment was proposed. In succession a set of testing equipment found on 0.8″ absolute optoelectronic encoder was established. The testing precision of testing equipment was analyzed carefully from the testing method error and the encoder's error aspects. Finally, scanning mirror's motion precision testing experimentation was carried out by the testing equipment. The testing results indicate that the scanning mirror's position precision is better than 3″±1.2″, speed precision is 5.6%±1.29% when 4 times compensation and 3.85% ±1.29%when 6 times compensation. These precision results meet the requirements of imaging spectrometer for scanning mirror. Favorable imaging property of the imaging spectrometer proves that the proposed testing method and equipment is suitable for scanning mirror's check and accept.